I never use replace method for all of my mods so I can't really tell what car to replace and where to replace it.

You can replace any cars in the game as long as you replace the data as well.

You can use search function in OpenIV (Ctrl+F3) to locate the car you want to replace.

DO NOT REPLACE WHOLE DATA FILES.
Open the files, copy the lines and replace the data lines of the car you want to replace.

You can ask me or just comment in the mod release page if you don't know the location of the car you want to replace
(because there are some cars that get updates which made the game have multiple files of the same cars and you need to replace the latest update to get the mod working)